JSON Formatter

JSON Formatter — Pretty Print JSON Online Free

Free online · Instant results · No signup

Free JSON formatter to pretty print JSON online. Indent, clean, and copy API payloads in your browser—no signup, no upload.

Paste compressed or messy JSON and turn it into readable, indented output in one click. This JSON formatter runs in your browser—ideal when you need to pretty print an API response from Postman, Chrome DevTools, or a log file without sending the payload to a third-party server.

About JSON Formatter

Minified JSON is great for networks and terrible for humans. When a webhook body or Prisma seed file arrives as one long line, finding a missing comma or nested key wastes minutes. Fake Data Hub’s JSON formatter pretty-prints that payload with clear indentation so you can scan objects, arrays, and nested fields the way you would in VS Code—without opening an editor.

Paste your JSON, click Format, and copy the result. Invalid JSON returns a clear error message instead of a blank screen. Note: standard JSON does not allow duplicate keys; if your input repeats the same key, the formatter follows normal JSON.parse rules and keeps the last value. That is expected behavior, not a bug.

Backend engineers use this page to clean responses before pasting into tickets. Frontend developers format fixture files before code review. QA engineers pretty-print failing payloads from Cypress or Playwright runs. Everything stays on your device for typical transforms—handy when the JSON includes staging tokens you should not upload to random websites.

How to Use JSON Formatter

  1. Paste your JSON into the input box (minified or partially formatted is fine).
  2. Click Format to pretty-print with standard indentation.
  3. If you see an error, fix the reported syntax issue and run Format again.
  4. Copy or download the cleaned JSON for your editor, ticket, or fixture file.

If Format fails, check for trailing commas, single quotes, or comments—plain JSON does not allow those. Convert from JSON5 or JS object literals before formatting.

Common Use Cases

Debug API responses from Postman or curl

Copy a raw response body, format it here, then scan nested error objects without fighting a single-line string in the terminal.

Clean fixtures before a pull request

Pretty-print seed JSON and mock files so reviewers can diff meaningful structure instead of one compressed line.

Read webhook and queue payloads

Format messages from Stripe, Shopify, or internal queues when logs only store compact JSON.

Teach and document JSON shapes

Paste examples into docs or Notion after formatting so teammates see field hierarchy clearly.

Why Use Fake Data Hub?

Fake Data Hub keeps JSON formatting free and local in the browser, next to JSON validate, minify, diff, and CSV convert tools on the same site—so you can move from messy payload to clean fixture without juggling five bookmarks.

Frequently Asked Questions

What is a JSON formatter?

A JSON formatter (or pretty printer) takes compact JSON and adds line breaks and indentation so objects and arrays are easy to read. Fake Data Hub’s tool does this instantly in your browser.

How do I pretty print JSON online?

Paste the JSON into the input area and click Format. The output panel shows indented JSON you can copy or download—no account required.

Is this JSON formatter free?

Yes. You can format as often as you need with no signup, no API key, and no paid plan.

Does the JSON formatter upload my data?

Formatting runs in your browser for normal use. Avoid pasting production secrets into any public tool if your security policy forbids it.

Why did duplicate keys disappear after formatting?

JSON objects cannot have two values for the same key. Parsers keep the last duplicate. If you need both values, rename keys or wrap them in an array before formatting.

Why does Format say my JSON is invalid?

Common causes are trailing commas, single quotes instead of double quotes, unquoted keys, or comments. Fix those syntax issues and try again.

Can I format JSON from Postman?

Yes. Copy the response body from Postman, paste it here, click Format, then paste the cleaned JSON into a ticket or fixture file.

Is this the same as a JSON beautifier?

Yes in practice—beautify and pretty print mean the same thing. We also offer a dedicated JSON Beautifier page if you prefer that search term.

How is this different from JSON Minifier?

Formatter adds whitespace for reading. Minifier removes whitespace for smaller payloads. Use formatter while debugging; minify before embedding compact fixtures.

Can I format a large JSON file?

Yes for typical API payloads and fixtures. Extremely huge files may be slower in the browser—split them or use a local editor for multi‑megabyte dumps.

Does it sort JSON keys?

No. Key order from the parsed object is preserved as JavaScript provides it. Sorting keys is a separate step if your team requires canonical order.

Can I use this instead of VS Code format?

VS Code is great inside a project. This page is faster when you just need to format a snippet from chat, email, or DevTools without creating a file.

Does it support JSON with comments?

No. Standard JSON rejects comments. Strip // or /* */ comments first, or convert from JSONC in your editor.

What about JSON5 or JavaScript objects?

This tool expects strict JSON (double quotes, no trailing commas). Convert JS object literals to JSON before formatting.

Can I download the formatted JSON?

Yes. After Format succeeds, use Download to save a .json file, or Copy to paste into your editor.

Is there a JSON validator on Fake Data Hub too?

Yes. Use JSON Validator when you only need a pass/fail check and an error message, or stay on this page when you want pretty output in one step.